Health officials are alerting doctors and patients in the US that Sanofi-Aventis' heart drug Multaq has been linked with rare cases of severe liver injury, of which two lead to acute liver failure.

Multaq (dronedarone) was approved in the US and Europe (and other regions) in 2009 for the treatment of abnormal heart rhythm in patients, on the back of data from seven clinical trials, including one that showed that it cut the number of hospital days in patients with atrial fibrillation by 28% compared to placebo and the total length of time spent in hospital for heart-related reasons by 35%. 

Marketing clearance in the US was, however, only issued alongside a Risk Evaluation and Mitigation Strategy, in order to prevent use of the drug in patients with severe heart failure or those recently hospitalised for the condition, after data showed these subsets to have a greater than two-fold increase in the risk of death.

Now, in another black mark against Multaq's safety profile, the US Food and Drug Administration said it is adding information about the potential risk of liver injury to the WARNINGS AND PRECAUTIONS and ADVERSE REACTIONS sections on its label, following several reports of hepatocellular liver injury and hepatic failure in patients treated with the drug.

The agency said it has received two post-marketing reports of acute hepatic failure - 4.5 and 6 months after treatment initiation - in patients with previously normal levels of hepatic serum enzymes, with these patients actually needing liver transplants.

But according to Seamus Fernandez, an analyst at Leerink Swann, the new warnings are unlikely to hurt US sales of Multaq too much, which he predicts will hit $521 million by 2016, reports Bloomberg.